Many studies have shown that oxidative modification of low density lipoprotein (LDL) represents a critical step in the development of atherosclerosis. LDL subjected to an oxidative stress, which can occur when the lipoprotein is exposed to oxidants, results in the formation of a particle whose biological properties contribute to the atherogenic process. Protecting against LDL oxidative modification is mediated via a host of different antioxidant systems, which are present in both the lipophilic and aqueous compartments.